Fig. 4. HERV-derived epitopes induce polyfunctional CD8⁺ T cell responses.

(A) Schematic representation of the in vitro priming protocol. (B) Representative example [healthy donor 2 (HD2)] of dextramer staining of peptide-stimulated (bottom right) and unstimulated (bottom left) PBMCs gated on the CD8⁺ T cells. CMV pp65–stimulated (top right) and unstimulated (top left) PBMCs are used as controls. (C) Summary of the results obtained with PBMCs from 11 HLA-A2–positive HD (HD1 to HD11, one donor per line). (D) Plots of IFN-γ (left panels), IFN-γ and tumor necrosis factor–α (TNF-α) (center panels), or IFN-γ and CD107a (right panels) staining gated on CD8⁺ T cells. PBMCs were stimulated with peptide (here P6, top line), no peptide (central line,) or CMV pp65 peptide (bottom line). Plots (HD5) are representative of the data summarized in fig. S4E. (E) Mean number and SD of IFN-γ⁺, Grz-b⁺, and double IFN-γ⁺ Grz-b⁺ spots counted on Fluorospot after stimulation of HLA-A2–positive PBMCs with different peptides (duplicates). Representative wells (HD2) are shown on the right: IFN-γ, Grz-b, and double-positive spots for PBMCs alone and 10:1 PBMC:T2 cocultures using either unstimulated PBMCs, P1-stimulated PBMCs, or CMV pp65–positive control PBMCs. pp65, phosphoprotein 65; Unstim, unstimulated.